Abstract: A defect inspection device (100) includes an excitation unit that excites an elastic wave, an irradiation unit (2) that applies laser lights, a measurement unit (3) that measures the interfered laser lights, and a control unit that acquires vibration state information which is information about a state of the elastic wave excited in an inspection target (P) for a plurality of frequencies by changing a frequency of excitation vibration caused by the excitation unit in order to excite the elastic wave in the inspection target (P), and extracts recommended frequencies (F) recommended for inspecting a defect of the inspection target (P) from among the plurality of frequencies based on the acquired vibration state information for the plurality of frequencies.

Abstract: A part defect testing system includes a hammer beam system that provides laser light having a first wavelength. A read-out beam system provides laser light having a second wavelength. A control system is used to direct the generated hammer beam laser light toward a first position on a part to provide an acoustic hammer pulse that induces surface movement of the part. An areal camera is arranged to produce an interferogram derived from reading surface movement of the part using the read-out beam directed to a second position on the part.

Abstract: A photoacoustic remote sensing system for imaging a subsurface structure in a sample, comprising exactly one laser source configured to generate a pulsed or intensity-modulated excitation beam configured to generate ultrasonic pressure signals in the sample at an excitation location, and an interrogation beam incident on the sample at the excitation location, a portion of the interrogation beam returning from the sample that is indicative of the generated ultrasonic pressure signals, an optical system configured to focus the excitation beam and the interrogation beam below a surface of the sample, a detector configured to detect the returning portion of the interrogation beam, and a processor configured to calculate an image of the sample based on a detected intensity modulation of the returning portion of the interrogation beam from below the surface of the sample.

Abstract: A method of operating a light detection and ranging (LIDAR) system is provided that includes generating a beam of polarized light; and transforming a polarization state of the beam of polarized light at a rate faster than a rate of data collection at a plurality of detectors configured to detect light reflected from a target for the purpose of speckle-reduction.

Abstract: The present invention relates to a method for generating control data for the secondary machining of a solid body (1), in particular wafer, which is modified by means of laser beams (10). The interior of said solid body (1) has multiple modifications (12), said modifications (12) having been produced by means of laser beams (10).

Abstract: An ultrasonic scanner acquires a gain profile including gain values for corresponding travel times in ultrasonic echoes reflected by a reference object. An ultrasonic probe signal is sent toward a test object. In response, an ultrasonic echo reflected by the test object is received at the scanner. A time of arrival of the echo is estimated. The gain profile is aligned with the echo according to the estimated time of arrival of the echo. The echo is amplified using the aligned gain profile and the amplified echo is digitized before being attenuated using the aligned gain profile. An actual time of arrival of the echo is calculated based on the attenuated digitized echo. The gain profile is re-aligned with the attenuated digitized echo according to the actual time of arrival of the echo. The attenuated digitized echo is re-amplified using the re-aligned gain profile to obtain a gain-corrected echo.

Abstract: A method and a system for photoacoustic inspection of a part are provided herein. The method may include the following steps: photo-acoustically exciting a predetermined position in a predetermined region on a part by pulsed laser illumination, to yield ultrasonic excitation of the part; coherently illuminating a predetermined location in the predetermined region on the part; detecting an illumination scattered from the predetermined location; determining, based on the scattered illumination, a plurality of sequence of two or more temporally-sequential de-focused speckle pattern images, wherein each of the sequences corresponds to one of the predetermined illuminated locations; and determining a set of translations, each determined based on the sequences, wherein each translation in the set is determined based on two temporally-sequential speckle patterns images in the respective sequence.

Abstract: A non-destructive opto-acoustic metrology device detects the presence and location of non-uniformities in a film stack that includes a large number, e.g., 50 or more, transparent layers. A transducer layer at the bottom of the film stack produces an acoustic wave in response to an excitation beam. A probe beam is reflected from the layer interfaces of the film stack and the acoustic wave to produce an interference signal that encodes data in a time domain from destructive and constructive interference as the acoustic wave propagates upward in the film stack. The data may be analyzed across the time domain to determine the presence and location of one or more non-uniformities in the film stack. An acoustic metrology target may be produced with a transducer layer configured to generate an acoustic wave with a desired acoustic profile based on characteristics of the film stack.

Abstract: A photoacoustic remote sensing system for imaging a subsurface structure in a sample, comprising exactly one laser source configured to generate a pulsed or intensity-modulated excitation beam configured to generate ultrasonic pressure signals in the sample at an excitation location, and an interrogation beam incident on the sample at the excitation location, a portion of the interrogation beam returning from the sample that is indicative of the generated ultrasonic pressure signals, an optical system configured to focus the excitation beam and the interrogation beam below a surface of the sample, a detector configured to detect the returning portion of the interrogation beam, and a processor configured to calculate an image of the sample based on a detected intensity modulation of the returning portion of the interrogation beam from below the surface of the sample.

Abstract: An additive manufacturing apparatus according to one embodiment includes a manufacturing unit, an elastic wave generation unit, an elastic wave detection unit, and an inspection unit. The manufacturing unit sequentially stacks a layer formed by emitting a first energy beam to a material and solidifying the material. The elastic wave generation unit emits a second energy beam to a manufactured object including the layer and generates an elastic wave propagating in the manufactured object. The elastic wave detection unit detects the elastic wave. The inspection unit inspects the manufactured object on the basis of a detection result from the elastic wave detection unit.

Abstract: An all-optical ultrasonic detection device based on light-induced ultrasound and laser interference. In the device, a first laser is connected to an optical switch, the optical switch is connected to a dielectric film and a second laser generates a reference laser beam and a plurality of detection laser beams. The reference laser beam generates a first frequency-shifted reference laser beam and a plurality of second frequency-shifted reference laser beams. The first frequency-shifted reference laser beam generates a carrier signal. The detection laser beams are reflected by the dielectric film and then interfere with the second frequency-shifted reference laser beams. The interference light passes through a fourth fiber coupler and reaches a second photodiode to generate a frequency-modulated signal. The frequency-modulated signal and the carrier signal are input to a frequency mixer to generate a mixed signal. An acquisition unit is configured to obtain a vibration signal for the to-be-detected object.

Abstract: Semiconductor metrology systems based on directing radiation on a wafer, detecting second harmonic generated (SHG) radiation from the wafer and correlating the second harmonic generated (SHG) signal to one or more electrical properties of the wafer are disclosed. The disclosure also includes parsing the SHG signal to remove contribution to the SHG signal from one or more material properties of the sample such as thickness. Systems and methods described herein include machine learning methodologies to automatically classify obtained SHG signal.

Abstract: A system calibrates luminance of an electronic display. The system includes an electronic display, a luminance detection device, and a controller. The luminance detection device is configured to measure luminance parameters of active sections of the electronic display. The controller is configured to instruct the electronic display to activate sections in a sparse pattern and in a rolling manner and instruct the luminance detection device to measure luminance parameters for each of the active sections in the sparse pattern. The controller generates calibration data based on the measured luminance parameters of sections in the sparse pattern.

Abstract: A system for detecting vibrations from a surface is provided. The system includes a coherent light source for projecting a multi-beam pattern onto the surface and an imaging device for mapping a speckle field generated by each spot formed on the surface by the multi-beam pattern to a unique region of an imaging sensor. The system further includes a processor for processing speckle field information received by the imaging sensor and deriving surface vibration information.

Abstract: A phase shift detector includes: an interferometer; and a microwave probe in electrical communication with the interferometer, the microwave probe including: a primary shield electrode; and a transmission electrode disposed proximate to the primary shield electrode, the transmission electrode and the primary shield electrode being exposed and arranged to produce an electric field, wherein the transmission electrode is isolated electrically from the primary shield electrode.

Abstract: The present disclosure relates to a full-field Z-direction displacement measurement system. Dynamic measurement is achieved on the basis of laser shearing speckle interferometry by using a spatial domain phase shift method. The homogeneity and similar measurement accuracy of the laser shearing speckle interferometry and the Doppler interferometry are further used to help the laser shearing speckle interferometry to implement absolute displacement measurement by using the single-point time domain Doppler interferometry. By means of the improvements in these aspects, the measurement system of the present invention can achieve full-field Z-direction displacement measurement, high-precision full-field absolute value vibration measurement and transient depth measurement, and can have important applications in depth measurement, three-dimensional sensing, vibration measurement in aerospace and the depth measurement in new material characterization detection and other fields.

Abstract: A method for inspecting an additive manufacturing process in which a directed energy source is used to create a weld pool at an exposed build surface of a mass of powdered material, and selectively fuse the powdered material to form a workpiece. The inspection method includes: using a noncontact method to generate an acoustic wave in the build surface; using a noncontact method to measure displacement of the build surface in response to the acoustic wave; and determining at least one sub-surface material property of the workpiece by analyzing the displacement of the build surface.

Abstract: Method and system for measuring vibration in two or three directions in objects (12) by using three illumination light beams (11A-C) for measurement of in-plane vibrations in two directions, where one of the three illumination light beams (11A-C) is common for the two in-plane measurements, and where the three illumination light beams (11A-C) are configured to provide free space at one side of the object (12) for easier access to the object. The method and system is further arranged for using two illumination light beams (30A-B) for measuring vibrations in the object (12) in a third direction, which third direction is out-of-plane direction, where one illumination light beam (30A) is illuminating the object (12) through an imaging objective (16) and one illumination light beam (30B) is used as reference beam.

Abstract: A nonlinear terahertz (THz) spectroscopy technique uses a sample illuminated by two THz pulses separately. The illumination generates two signals BA and BB, corresponding to the first and second THz pulse, respectively, after interaction with the sample. The interaction includes excitation of at least one ESR transition in the sample. The sample is also illuminated by the two THz pulses together, with an inter-pulse delay ?, generating a third signal BAB. A nonlinear signal BNL is then derived via BNL=BAB?BA?BB. This nonlinear signal BNL can be then processed (e.g., Fourier transform) to study the properties of the sample.

Abstract: To implement an analysis result provision system that can acquire an analysis result of a target substance without transferring the substance when the substance is analyzed using plasma light information occurred from plasma area where the substance is turned to plasma state, a provision system of analysis result includes an analytical terminal that turns a target substance to plasma state and acquires plasma light information occurred from plasma area, and a host computer. The host computer includes host side communication part that acquires plasma light information via telecommunication line, and information analysis part that analyzes the target substance using plasma light information acquired by the host side communication part. The host side communication part transmits the analysis result of the target substance to the sender of the plasma light information. The analysis result is obtained by the analysis of the information analysis part using plasma light information.

Abstract: A photoacoustic wave induced in a subject to be examined by illumination of the subject to be examined with light is detected. A first photoacoustic image corresponding to a frequency component less than or equal to a predetermined frequency and a second photoacoustic image corresponding to a frequency component higher than a predetermined frequency are generated based on a detection signal of the detected photoacoustic wave. The first photoacoustic image and the second photoacoustic image are combined together by placing, on a pixel in the first photoacoustic image the pixel value of which is less than or equal to a threshold, a pixel in the second photoacoustic image corresponding to the pixel in the first photoacoustic image.

Abstract: The invention concerns an apparatus (1) for producing three-dimensional objects (6) layer by layer using a powdery material which can be solidified by irradiating it with a beam (4) of charged particles, said apparatus (1) comprising means for successive application of powder layers to a work table, and a radiation gun (3) for delivering said beam (4) of charged particles, wherein the inventive apparatus (1) comprises a powder-lifting detection device (10, 10a, 10b, 10c, 10d, 10e) capable of generating a signal (S) upon detection of lifting of powdery material from the working area (5).

Abstract: Techniques are described for characterizing a receiver front end of a pluggable optical module. The pluggable optical module receives an optical signal that includes a first portion having a first polarization and a second portion having a second polarization. The first portion and second portion are not coherent with one another and the power of the first portion and second portion is equal.

Abstract: An optical sensing device can receive a speckle pattern generated by a laser's interaction with acoustically stimulated tissue. A computing device can identify one or more characteristics within the received speckle pattern. The computing device can then identify a match of the one or more characteristics to a user biometric signature stored within a storage device. Based upon the identified match, the system can authenticate a user within a computer system.

Abstract: An apparatus and a method for detecting surface motion of an object subject to ultrasound are disclosed. The method comprises generating a laser beam, dividing the laser beam into a reference beam and an object beam to be directed onto the surface, thereby producing a scattered object beam, introducing a small-amplitude modulation in the optical path difference between the reference beam and the scattered object beam, detecting the interference between the scattered object beam and the phase modulated reference beam using a plurality of detecting elements to generate a plurality of electrical interference signals, wherein the electrical interference signals each comprise a wanted signal component indicative of the surface motion and a noise signal component, and processing the electrical interference signals to determine the surface motion of the object.

Abstract: An automatically adjustable method for use in opto-acoustic metrology or other types of metrology operations is described. The method includes modifying the operation of a metrology system that uses a PSD style sensor arrangement. The method may be used to quickly adjust the operation of a metrology system to ensure that the data obtained therefrom are of the desired quality. Further, the method is useful in searching for and optimizing data that is or can be correlated to substrate or sample features or characteristics that of interest. Apparatus and computer readable media are also described.

Abstract: A material sensing apparatus comprises an excitation source configured to induce waves in a workpiece, and an optical waveguide interferometer configured to sense the induced waves in the workpiece. The optical waveguide interferometer comprises a probe segment having a probe segment end, and an adjustable coupler configured to permit setting a gap between the probe segment end and the workpiece. A controller is coupled to the adjustable coupler and configured to set the gap between the probe segment end and the workpiece.

Abstract: A biological sensing apparatus comprises an excitation source configured to induce waves in a biological target, and an optical waveguide interferometer configured to sense the induced waves in the biological target. The optical waveguide interferometer comprises a probe segment having a probe segment end, and an adjustable coupler configured to permit setting a gap between the probe segment end and the biological target. A controller is coupled to the adjustable coupler and configured to set the gap between the probe segment end and the biological target.

Abstract: A sensing apparatus comprises an excitation source configured to induce waves in a target, and a fiber optic interferometer configured to sense the induced waves in the target. The fiber optic interferometer comprises a probe segment having a probe segment end, and an adjustable coupler configured to permit setting a gap between the probe segment end and the target. A controller is coupled to the adjustable coupler and configured to set the gap between the probe segment end and the target.

Abstract: The invention relates to a method for photoacoustic tomography of a sample, deformations on a measurement surface of the sample being measured as a function of location and time, the deformations resulting from the absorption of a pulsed excitation radiation on at least one spectrally addressable target structure in the sample interior while emitting thermomechanical pressure waves in the direction of the measurement surface, and the measured deformations being fed to a reconstruction method for determining the position of the target structure in the sample interior.

Abstract: An apparatus and a method capable of measuring large deformation with a high accuracy and dynamically, using speckle interference, utilizes an optical path where one laser beam out of two laser beams becomes non-collimated light and a plane parallel transparent plate, and can form carrier fringes. More specifically, the transparent plate is arranged on the optical path where the non-collimated light is formed, or is removed from the optical path, or a refractive index, or a thickness of the transparent plate arranged on the optical path, or a tilt angle relative to an optical axis is changed. The phase analysis can be performed from fringe images corresponding to the deformation, by performing repetitively the above-described processing and acquisition of the speckle interference pattern.

Abstract: High speed autofocus interferometric inspection systems and methods are discussed in this Application. In accordance with some embodiments, an inspection system can generally include a laser module, an interferometer module, and a system controller. The laser can produce laser pulses to excite a device such as a silicon wafer, chip capacitor or chip packaged/silicon die containing a plurality of solder bumps into vibration. The interferometer module can be disposed to receive reflected laser energy from the device to sense vibration displacements created in the device with the laser pulses. The system controller to receive vibration data from the interferometer, the system controller configured to output a control signal for adjusting a relative distance and position between the laser module and the device. Other aspects, features, and embodiments are also claimed and discussed.

Abstract: A pattern includes a spatial configuration of color codes. Each color code is a unique configuration of colors selected from a number of basis colors. The color codes each include the same number of colors.

Abstract: A material sensing apparatus includes an excitation source configured to induce waves in a workpiece, and an optical waveguide interferometer configured to sense the induced waves in the workpiece. The optical waveguide interferometer includes a plurality of optical couplers and interconnecting optical fibers arranged to define a reference arm, a measurement arm, and a probe segment coupled to the reference arm and the measurement arm and having a probe segment end to be positioned adjacent the workpiece. An optical path length adjustor is coupled to the reference arm. A controller cooperates with the optical path length adjustor and the first optical detector. The controller is configured to adjust an optical path length of the reference arm to maintain a constant relationship with respect to an optical path length of the measurement arm, and to generate workpiece data based upon the first optical detector.

Abstract: A sensing apparatus includes an excitation source configured to induce waves in a target, and an optical waveguide interferometer configured to sense the induced waves in the target. The optical waveguide interferometer includes a plurality of optical couplers and interconnecting optical fibers arranged to define a reference arm, a measurement arm, and a probe segment coupled to the reference arm and the measurement arm and having a probe segment end to be positioned adjacent the target. An optical path length adjustor is coupled to the reference arm. A controller cooperates with the path length adjustor and is configured to adjust an optical path length of the reference arm to maintain a constant relationship with respect to an optical path length of the measurement arm.

Abstract: A biological sensing apparatus includes an excitation source configured to induce waves in a biological target, and an optical waveguide interferometer configured to sense the induced waves in the biological target. The optical waveguide interferometer includes a plurality of optical couplers and interconnecting optical fibers arranged to define a reference arm, a measurement arm, and a probe segment coupled to the reference arm and the measurement arm and having a probe segment end to be positioned adjacent the biological target. An optical path length adjustor is coupled to the reference arm. A controller cooperates with the optical path length adjustor and a first optical detector. The controller is configured to adjust an optical path length of the reference arm to maintain a constant relationship with respect to an optical path length of the measurement arm, and to generate biological target data based upon the first optical detector.

Abstract: A biological sensing apparatus comprises an excitation source configured to induce waves in a biological target, and an optical waveguide interferometer configured to sense the induced waves in the biological target. The optical waveguide interferometer comprises a probe segment having a probe segment end, and an adjustable coupler configured to permit setting a gap between the probe segment end and the biological target. A controller is coupled to the adjustable coupler and configured to set the gap between the probe segment end and the biological target.

Abstract: A sensing apparatus comprises an excitation source configured to induce waves in a target, and a fiber optic interferometer configured to sense the induced waves in the target. The fiber optic interferometer comprises a probe segment having a probe segment end, and an adjustable coupler configured to permit setting a gap between the probe segment end and the target. A controller is coupled to the adjustable coupler and configured to set the gap between the probe segment end and the target.

Abstract: A material sensing apparatus comprises an excitation source configured to induce waves in a workpiece, and an optical waveguide interferometer configured to sense the induced waves in the workpiece. The optical waveguide interferometer comprises a probe segment having a probe segment end, and an adjustable coupler configured to permit setting a gap between the probe segment end and the workpiece. A controller is coupled to the adjustable coupler and configured to set the gap between the probe segment end and the workpiece.

Abstract: The present invention provides for a novel method and apparatus for the simultaneous generation and detection of optical diffraction interference pattern on a photo detector. The monitoring method and apparatus disclosed herein comprises of a (any) continuous wave coherent collimated beam of light (or a laser) falling on an (any) optically reflective coating on the surface of the body with inherent vibrations, or with manifest vibrations induced from another source through any medium where the said light is reflected, and then received on the surface of a (any) photo detector in such a way that the received light falls partially on the active sensing area, and partially on the outer perimeter of the active sensing area.

Abstract: An apparatus and a method for detecting surface motion of an object subject to ultrasound are disclosed. The method comprises generating a laser beam, dividing the laser beam into a reference beam and an object beam to be directed onto the surface, thereby producing a scattered object beam, introducing a small-amplitude modulation in the optical path difference between the reference beam and the scattered object beam, detecting the interference between the scattered object beam and the phase modulated reference beam using a plurality of detecting elements to generate a plurality of electrical interference signals, wherein the electrical interference signals each comprise a wanted signal component indicative of the surface motion and a noise signal component, and processing the electrical interference signals to determine the surface motion of the object.

Abstract: A laser maintenance apparatus including a laser irradiation device which includes a first optical element for irradiating detection laser light on a test object to detect an ultrasonic wave; a second optical element for irradiating generation laser light on a test object so as to excite the ultrasonic wave; and an optical system container for containing the first and second optical element. The reflection direction of the first optical element and the reflection direction of the second optical element are arranged at an angle along the circumferential direction of the test object. The light reflected by the first optical element is irradiated at a position different than light reflected by the second optical element, and the laser irradiation positions of the light reflected by the first and second optical elements are different in the axial direction and the circumferential direction of the test object.

Abstract: A laser beam irradiation apparatus includes a laser beam oscillation unit including a pulse laser beam oscillator for oscillating a pulse laser beam and a cycle frequency setting unit for setting the cycle frequency, an acousto-optic deflection unit for deflecting the optical axis of the pulse laser beam oscillated from the laser beam oscillation section, and a control unit for controlling the acousto-optic deflection unit. The control unit outputs a driving pulse signal having a predetermined time width including a pulse width of the pulse laser beam oscillated from the pulse laser beam oscillator to the acousto-optic deflection unit based on the cycle frequency setting signal from the cycle frequency setting section.

Abstract: A laser ultrasonic measurement system includes a first and a second laser source configured to generate a first and a second laser beam, respectively. A movable mechanical link is arranged to transmit the first laser beam. The movable mechanical link is formed by a plurality of rigid sections interconnected by rotating joints. A robot is configured to support and control the movement of at least a section of the mechanical link to transmit the first laser beam to an object. An optical scanner is positioned proximate to the mechanical link. The optical scanner is configured to direct the first and second laser beams onto the object. An interferometer is optically coupled to the optical scanner. The interferometer is configured to receive reflected light from the object and in response generate an electrical signal. The first laser source is kinematically mounted in a housing assembly.

Abstract: Remote seismic surveying systems and methods are disclosed. At least some embodiments illuminate a water or ground surface with a beam from a coherent electromagnetic wave source. Reflected electromagnetic energy is focused onto an image plane where it combines with a reference beam to form an interference pattern. Electronics track the intensity versus time for multiple points in the image and derive displacement signals for various physical locations in the survey region. These displacement signals are associated with seismic source firing times and locations before being stored as seismic traces in a survey database. Some variations use the reflected electromagnetic energy to create multiple interference patterns that vary due to different path length differences, thereby eliminating signal phase ambiguities.

Abstract: Low-cost interface property measuring device and method enabling high-precision and simple measurement of an interface property.

Abstract: A laser ultrasonic inspection system comprises laser sources configured to generate laser beams, an optical scanner configured to direct the laser beams onto an object thereby generating ultrasonic waves in the object and illuminating the object, an interferometer configured to generate an electrical signal in response to the reflected light, and a radiation restricting inspection chamber for housing the object. Another laser ultrasonic inspection system comprises a radiation restricting inspection chamber, laser sources located outside of the inspection chamber, an optical scanner located inside the inspection chamber, a visible laser tracer representative of the orientation of the laser beams; an interferometer, a scanner positioning mechanism, and an object positioning mechanism. A method for inspecting an object comprises the steps of positioning an object inside of an inspection chamber, defining a scanning profile, and directing laser beams onto the object according to the inspection profile.

Abstract: A device detects underfill voids and solder ball defects via laser generation and laser detection of an ultrasonic wave at the top surface of flip chips. High resolution is provided by using small laser spot sizes and closely-spaced laser beams of wavelengths that are absorbed near the surface of the semiconductor. Improved spatial resolution and rejection of unwanted scattered waves can be attained by limiting the time frame of the ultrasonic waveform to the time required for the first longitudinal wave reflection from the bottom of the flip chip. The laser beam spacing can be reduced by using probe and detection beams of different wavelengths. Resolution of less than 100 ?m features was demonstrated for silicon flip chips.

Abstract: A method of measuring at least one property including a magnetic property of target material is provided. A pump pulse train having one or more pump pulses is generated. The target material is irradiated with at least a portion of the one or more pump pulses so as to cause transient perturbation in the target material. At least one probe pulse train is generated having one or more probe pulses. The target material is irradiated with at least a portion of the one or more probe pulses to obtain one or more reflected probe pulses which are modulated based on the transient perturbation. A time interval between a time at which the target material is irradiated by each of the pump pulses and a time at which the target material is irradiated by each of its corresponding probe pulses is controlled. Each modulated probe pulse is detected.

Abstract: A surface inspecting method including irradiating a laser light to a test object to generate an ultrasonic wave, irradiating a second laser light at a position apart by a known distance from a position where the laser light is irradiated and receiving a reflection light thereof, and correcting a generation surface wave of a received ultrasonic wave by using an ultrasonic wave other than the generation surface wave to thereby detect a flaw of the test object. A characterization of the generation surface wave is divided or integrated by the same characterization of the ultrasonic wave other than the generation surface wave included in an output signal to obtain a performance index value and obtain a depth of the flaw by applying the performance index value to a calibration curve in which a corresponding relation between the performance index value and the depth of the flaw is obtained preliminarily.